Patent Application
20080195125
The present invention relates to medical devices and more particularly, to devices for anastomosis. The invention further provides methods of manufacturing devices for anastomosis and methods of treating vessel impairment with devices for anastomosis.
Anastomosis is the process of connecting two or more ends of a hollow tube to a vessel in order to provide an alternate channel for fluid flow. In humans, surgical anastomosis is performed to provide an alternate channel for the flow of bodily fluids.
Anastomosis is often an appropriate surgical procedure when body vessels become impaired due to a variety of factors. For example, blood vessels may be impaired by becoming clogged, blocked, narrowed, or otherwise impaired. When the blood vessels of the vascular system fail to function properly, severe health consequences can result, including death. Among the most serious forms of vascular impairment is coronary artery atherosclerosis. According to one estimate, close to 14 million Americans have coronary artery atherosclerosis. Annually, an estimated 1.5 million people develop the most severe type of coronary artery disease—acute myocardial infarction. Roughly a third of the people struck by acute myocardial infarction die as a result of this type of coronary artery disease.
It is estimated that in 2006 approximately 250,000 coronary bypass surgeries will be performed in the United States. It is common during coronary bypass surgery to perform as many as five anastomoses. Although coronary bypass surgery is an invasive procedure, it is often the only available treatment option. However, there are drawbacks associated with coronary bypass surgery and other types of bypass surgery. Complications can arise from bypass surgery including myocardial infarction, cardiac arrhythmias, infection, edema, thrombosis, blood clot formation, restenosis, nerve injury, and graft occlusion.
During traditional coronary bypass surgery, the sternum is cut down the middle with a bone saw and the chest is opened. The surgeon may elect to place the patient on cardiopulmonary bypass. In addition, the surgeon may use stabilizing devices to hold the heart still. After locating the impaired artery, a surgeon typically creates an incision in the artery on one side of the blood vessel impairment. Next, the surgeon sutures a graft to the artery with between eight and fourteen evenly-spaced sutures. After one end is attached, the surgeon creates an incision on the other side of the blood vessel impairment and the other end of the graft is sutured to the artery. Usually, a surgeon will check for leakages to ensure that the graft is securely in place and correctly aligned within the body. Finally, the surgeon closes the chest cavity after all the necessary anastomoses are complete.
One problem with bypass surgery is that the internal structures of the body are left exposed for an extended length of time. As the length of exposure increases, the risk of infection and other complications may increase. Not only is the risk to the patient increased by a lengthier procedure, the cost of such a procedure likewise increases. For example, more medications, such as anesthesia, are needed for longer procedures. Similarly, additional staff resources, such as staff time and equipment time, are required as the length of a procedure increases.
Another problem with traditional bypass surgery is that the skill of the surgeon may negatively affect the success of the bypass procedure. The skill of a surgeon in suturing a graft to existing arteries may determine whether leakages occur or result in other associated problems.
In addition to traditional methods of anastomoses, devices for anastomosis have been developed in attempts to address some of these problems. However, the available devices have had problems including occlusion, thrombus, stenosis at the connector site, aortic dissection associated with device deployment, graft kinking, and postoperative device detachment. Therefore, it is apparent to the inventor that an improved anastomosis device would be desirable.
An anastomosis device including a stent structure is described. The anastomosis device comprises a graft tube, a first end portion, and a second end portion. The graft tube comprises a first end, a second end, and a lumen extending therethrough. The first end portion is connected to the first end of the graft tube and the first end portion is adapted to be attached to an incision in a vessel. The second end portion includes a stent structure. Furthermore, the second end portion is connected to the second end of the graft tube and is adapted to be attached to another incision in the vessel. The second end portion comprises a first part adapted to be connected to the second end of the graft tube. The first part is substantially cylindrical. A second part is substantially quonset-shaped and the first part is connected to the convex region of the second part. Additional details and advantages are described below in the detailed description
A method of using an anastomosis device is also described. First, an incision is created in a vessel. Next, a first end portion of an anastomosis device is attached to the incision. A second incision is then created in a vessel and a compressed second end portion of an anastomosis device is inserted through the second incision. Next, the second end portion is expanded to a generally relaxed state and a graft tube is attached to the second end portion.
The invention may be more fully understood by reading the following description in conjunction with the drawings, in which:
Referring to the drawings, and specifically to
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In
The described stent structure 36 may be self-expanding, balloon expandable, or may have both characteristics. For example, a zig-zag stent is a stent structure that has alternating struts and peaks (i.e., bends) and defines a generally cylindrical space. A “Gianturco Z stent” is a type of self-expanding zig-zag stent structure. Stent structures may be encapsulated, partially encapsulated, or not encapsulated. A variety of other stent structures and configurations are also contemplated by use of the term stent structure.
A stent structure 36 offers the advantage of providing desirable forces in a specific direction or directions. Desirable forces include resilient forces and radial forces. The forces provided by a stent structure 36 may, among other things, resist the collapse of tissue walls, maintain a desirable geometry, provide expansion force to hold a device in place, seal an aperture, or otherwise provide desirable effects. Furthermore, stent structures provide the advantage of being able to be inserted with a narrow profile through apertures such as the incision 24 shown in
The stent structures 36 described herein are preferably self-expanding and formed from a superelastic material. When stent structures 36 are comprised of superelastic material, they are capable of elastically expanding to a predictable shape and offer the advantage of being able to spring back from external forces. Typically, superelastic materials can achieve elastic strains of at least several percent. Upon removal of the applied stress, the elastic strain induced by the applied stress is recovered and the material returns to its original, undeformed configuration. One example of a superelastic material is NITINOL, which is a superelastic nickel-titanium alloy that can achieve an elastic strain of about 8%. In contrast, 3conventional metal alloys, such as 304 stainless steel, typically achieve elastic strains of only a fraction of a percent. Materials exhibiting superelastic behavior are sometimes referred to as shape memory materials or pseudoelastic materials.
Accordingly, the stent structures may comprise self-expanding struts. The self-expanding struts may be made out of stainless steel, superelastic materials such as NITINOL, or any other suitable material. The stent structure or stent structures may be formed from self-expanding stents such as Z-STENTS. Z-STENTS are available from Cook, Incorporated, Bloomington, Ind. USA.
In some embodiments, such as the embodiment shown in
In some embodiments, the graft tube comprises an extracellular matrix material. The “extracellular matrix” is typically a collagen-rich substance that is found in between cells in animal tissue and serves as a structural element in tissues. Such an extracellular matrix is preferably a complex mixture of polysaccharides and proteins secreted by cells. The extracellular matrix can be isolated and treated in a variety of ways. Following isolation and treatment, it is referred to as an “extracellular matrix material,” or ECMM. ECMMs may be isolated from submucosa (including small intestine submucosa), stomach submucosa, urinary bladder submucosa, tissue mucosa, renal capsule, dura mater, liver basement membrane, pericardium or other tissues.
Purified tela submucosa, a preferred type of ECMM, has been previously described in U.S. Pat. Nos. 6,206,931, 6,358,284 and 6,666,892 as bio-compatible, non-thrombogenic material that enhances the repair of damaged or diseased host tissues. U.S. Pat. Nos. 6,206,931, 6,358,284 and 6,666,892 are incorporated herein by reference. Purified submucosa extracted from the small intestine (“small intestine submucosa” or “SIS”) is a more preferred type of ECMM for use in this invention. Another type of ECMM, isolated from liver basement membrane, is described in U.S. Pat. No. 6,379,710, which is incorporated herein by reference. ECMM may also be isolated from pericardium, as described in U.S. Patent No. 4,502,159, which is also incorporated herein by reference.
Extracellular matrix materials such as purified tela submucosa, are substantially biocompatible and thus cause a reduced foreign body response when implanted within a body. Biocompatibility represents a problem for certain anastomosis devices. Some implanted biomaterials used for tissue repair initiate a foreign body reaction that causes encapsulation of the anastomosis device or a portion of the anastomosis device in rigid, fibrous scar tissue. Accordingly, a graft material comprising a biocompatible material is preferred.
Certain anastomosis devices include members, such as gripping hooks or connector wires, which attach to a vessel via a mechanism that causes trauma to a vessel by penetrating the inner surface of a vessel. Penetrating members apply a force at specific narrow points of contact in a manner that may damage a vessel. With a severe type of penetrating, the vessel wall is actually punctured by the penetrating members. For example, a device of U.S. Pat. No. 6,451,048 as shown in
Hooks and other devices for securing devices to vessels may have negative health consequences. Members that cause vessel trauma, such as gripping hooks which penetrate the inner surface of a vessel wall, may cause inflammation of the surrounding tissue. Inflammation may lead to an immune response whereby the foreign structure is encapsulated by new tissue growth which then occludes blood flow. In addition, inflammation may lead to thromboses or embolism. Alternatively, the trauma caused to the vessel may lead to a deterioration of the tissue wall around the foreign material, sometimes referred to as tissue erosion. In contrast, structures that apply a force over a surface area instead of applying force at a specific point or points may cause less vessel trauma.
In some embodiments, and as shown in
The incision 24 may be made in a variety of ways. For example, an incision 24 may be made from the outside of the vessel, such as is typically done with a scalpel or a punch device. For further example, the incision 24 may also be made from the inside of the vessel, such as with a blade that may be advanced vascularly within a catheter.
In other embodiments, the graft tube comprises a biocompatible polyurethane. Examples of biocompatible polyurethanes include THORALON® (Thoratec, Pleasanton, Calif.), BIOSPAN®, BIONATE®, ELASTHANE™, PURSIL™ and CARSOSIL™ (Polymer Technology Group, Berkeley, Calif.). As described in U.S. Patent Application Publication No. 2002/006552 A2, incorporated herein by reference, THORALON® is a polyetherurethane urea blended with a siloxane-containing surface modifying additive. Specifically, the polymer is a mixture of base polymer BPS-215 with an additive SMA-300.
THORALON® has been used in certain vascular applications and is characterized by thromboresistance, high tensile strength, low water absorption, low critical surface tension, and good flex life. THORALON® is believed to be biostable and to be useful in vivo in long term blood contacting applications requiring biostability and leak resistance. Because of its flexibility, THORALON® is useful in procedures involving larger vessels where elasticity and compliance is beneficial.
Biocompatible polyurethanes modified with cationic, anionic and aliphatic side chains may also be used. See, for example, U.S. Pat. No. 5,017,664. Other biocompatible polyurethanes include: segmented polyurethanes, such as BIOSPAN; polycarbonate urethanes, such as BIONATE; and polyetherurethanes such as ELASTHANE; (all available from POLYMER TECHNOLOGY GROUP, Berkeley, Calif.).
Other biocompatible polyurethanes include polyurethanes having siloxane segments, also referred to as a siloxane-polyurethane. Examples of polyurethanes containing siloxane segments include polyether siloxane-polyurethanes, polycarbonate siloxane-polyurethanes, and siloxane-polyurethane ureas. Specifically, examples of siloxane-polyurethane include polymers such as ELAST-EON 2 and ELAST-EON 3 (AORTECH BIOMATERIALS, Victoria, Australia); polytetramethyleneoxide (PTMO) and polydimethylsiloxane (PDMS) polyether-based aromatic siloxane-polyurethanes such as PURSIL-10, -20, and -40 TSPU; PTMO and PDMS polyether-based aliphatic siloxane-polyurethanes such as PURSIL AL-5 and AL-10 TSPU; aliphatic, hydroxy-terminated polycarbonate and PDMS polycarbonate-based siloxane-polyurethanes such as CARBOSIL-10, -20, and -40 TSPU (all available from POLYMER TECHNOLOGY GROUP). The PURSIL, PURSIL -AL, and CARBOSIL polymers are thermoplastic elastomer urethane copolymers containing siloxane in the soft segment, and the percent siloxane in the copolymer is referred to in the grade name. For example, PURSIL-10 contains 10% siloxane. These polymers are synthesized through a multi-step bulk synthesis in which PDMS is incorporated into the polymer soft segment with PTMO (PURSIL) or an aliphatic hydroxy-terminated polycarbonate (CARBOSIL). The hard segment consists of the reaction product of an aromatic diisocyanate, MDI, with a low molecular weight glycol chain extender. In the case of PURSIL-AL the hard segment is synthesized from an aliphatic diisocyanate. The polymer chains are then terminated with a siloxane or other surface modifying end group. Siloxane-polyurethanes typically have a relatively low glass transition temperature, which provides for polymeric materials having increased flexibility relative to many conventional materials. In addition, the siloxane-polyurethane can exhibit high hydrolytic and oxidative stability, including improved resistance to environmental stress cracking. Examples of siloxane-polyurethanes are disclosed in U.S. Pat. Application Publication No. 2002/0187288 A1, which is incorporated herein by reference.
In addition, any of these biocompatible polyurethanes may be end-capped with surface active end groups, such as, for example, polydimethylsiloxane, fluoropolymers, polyolefin, polyethylene oxide, or other suitable groups. See, for example the surface active end groups disclosed in U.S. Pat. No. 5,589,563, which is incorporated herein by reference.
In other embodiments, the graft tube comprises DACRON, expanded polytetrafluoroethylene, or other suitable graft materials.
While preferred embodiments of the invention have been described, it should be understood that the invention is not so limited, and modifications may be made without departing from the invention. The scope of the invention is defined by the appended claims, and all devices and methods that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein. Furthermore, the advantages described above are not necessarily the only advantages of the invention, and it is not necessarily expected that all of the described advantages will be achieved with all embodiments of the invention.
The present patent document claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No. 60/900,819, filed Feb. 12, 2007, which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60900819 | Feb 2007 | US |
